DETERMINATION OF BETA-CYCLODEXTRIN INCLUSION COMPLEX CONSTANTS FOR 3,4-DIHYDRO-2-H-1-BENZOPYRAN ENANTIOMERS BY CAPILLARY ELECTROPHORESIS

Chiral separation of 3,4-dihydro-2H-1-benzopyran derivatives by capill ary zone electrophoresis was achieved by employing beta-cyclodextrin ( beta-CD) as chiral selector. The effects of electrolyte composition (b eta-cyclodextrin concentration, ionic strength and pH of the buffer) o n the migration time, enantioselectivity, peak efficiency and resoluti on were investigated. As expected, there was an optimum beta-CD concen tration (C-opt) which gave maximum enantioselectivity. The stability c onstant for the beta-CD inclusion complex was determined for each enan tiomer of two 3,4-dihydro-2H-1-benzopyran derivatives. For each solute , the experimental value of C-opt agreed well with the value calculate d from the equation [C](opt) = 1/(KRKS)(1/2), where we used experiment al values for the inclusion complex constants (K-R,K-S). The enantiome ric separation of three 3,4-dihydro-2H-1-benzopyran derivatives was ac hieved using this optimization method, and baseline separation was obt ained in less than 15 min with an efficiency of between 300 000 and 60 0 000 theoretical plates.